Britain has reinforced its controversial military presence near Russia’s border as part of a NATO military alliance mission as government authorities claim the threat from Moscow has become more credible.

British media said on Monday that five Apache attack helicopters, each worth nearly $54 million, had been deployed to Estonia to reinforce NATO’s presence in the Baltic nation.

Defense Secretary Gavin Williamson said the deployment was necessary to deter a “credible” threat from Russia, Presstv Reported.

"It's a very credible threat that we see from Russia and part of the reason that we're deploying five Apache attack helicopters is making sure that we're constantly adapting to a changing situation, but this is about deterrents,” he said, adding “The enhancement of that deployment with the Apache attack helicopters is really vital and very, very important and it's been very warmly welcomed by so many nations.”

The deployment came as some 110 UK military personnel was also dispatched to Baltic countries to reinforce British troops deployed to NATO missions in the area. The personnel deployment, which comes as part of Operation CABRIT, will take the total number of UK troops in the region to around 1,000.

Williamson said that Britain was now “playing the largest role in enhanced forward presence with the largest number of service personnel deployed” in the Baltics.

The new UK military deployment could further anger Russia which has seen an expanded NATO presence along its western borders as a major threat. Moscow and NATO have been at odds since a political crisis erupted in Ukraine in 2014.

Britain has been a major contributor to NATO’s eastward expansion despite Russia’s threats that the policy could backfire.

Relations between Britain and Russia have further deteriorated over a poising attack in March last year on a former Russian spy in southern England.